Friction welding machine

ABSTRACT

A friction welding machine provided on its bed with a stationary head for tightly holding a first tube, a movable head for rotating a second tube being welded to the first tube, a work rest for securely supporting the second tube and a tail stock for pressing the second tube against the first tube and additionally equipped with outer upset-removing devices and an inner upsetremoving device, whereby the tubes are firmly friction-welded together and moreover an outer upset and an inner upset are removed grown at the joint of the tubes while the tubes are still mounted on the friction welding machine.

United States Patent n 1 Nomura et al.

[ 51 Oct. 1,1974

[ FRICTION WELDING MACHINE [75] Inventors: Hiroshi Nomura; MasayoshiUchida,

both of Yokohama, Japan [22] Filed: Apr. 25, 1973 [21] Appl. No.:354,437

[30] Foreign Application Priority Data July 7, 1972 Japan 47-67575 [52]U.S. Cl 228/2, 29/470.3, 156/580, 228/13 [51] Int. Cl B23k 27/00 [58]Field of Search 29/470.3; 228/2, 13; 156/73, 580

[56] References Cited UNITED STATES PATENTS 3,185,368 5/1965 Holloway etal 29/470.3 X

3,234,647 2/1966 Hollander et .al. 29/470.3 3,235,158 2/1966 Hollander29/470.3 X 3,439,853 3/1969 Deemie et al 228/2 3,599,857 8/1971 Loyd etal 29/470.3

Primary Examiner-Andrew R. Juhasz Assistant Examiner-Robert J. CraigAttorney, Agent, or Firm-Holman & Stern 5 7] ABSTRACT A friction weldingmachine provided on its bed with a stationary head for tightly holding afirst tube, a movable head for rotating a second tube being welded tothe first tube, a work rest for securely supporting the second tube anda tail stock for pressing the second tube against the first tube andadditionally equipped with outer upset-removing devices and an innerupsetremoving device, whereby the tubes are firmly friction-weldedtogether and moreover an outer upset and an inner upset are removedgrown at the joint of the tubes while the tubes are still mounted on thefriction welding machine.

8 Claims, 22 Drawing Figures PATENTED 3.838.807-

" sm-a0! e 670(680) 80 75 750 79 800 I 78 s9(?o) 77 76 FRICTION WELDINGMACHINE FIELD OF THE INVENTION This invention relates to a frictionwelding machine and more particularly to a type adapted to attain thefriction welding of two elongate tubes and remove outer and inner upsetsgrown at the joint of said tubes while they are still mounted on themachine.

DESCRIPTION OF THE PRIOR ART The prior art friction welding machine hasgenerally been designed to unite relatively short workpieces by frictionwelding or fix a short member such as a joint to an elongate tubesimilarly by friction welding. To date, however, there has not beenknown any friction welding machine which can friction-weld elongatetubes together.

The reason why the prior art can not effect the friction welding ofelongate tubes is that at least one of two workpiece tubes should berotated at high speed with one end thereof brought into contact with thefacing end of the other tube being friction-welded to said one tube, butthat since there has not been developed any suitable device capable ofunfailingly restricting the radial displacement of the rotating tube,this rotating tube is often subject to an excentr-ic rotation dependingon the magnitude of a force with which the tube is made to rotate or dueto the off center position which might occur during rotation, thuspresenting difficulties in attaining the accurate friction welding oftubes.

Further, even if the known friction welding machine can be made toeffect the friction welding of elongate tubes, there has not yet beendeveloped any such machine as can remove an inner upset grown at thejoints of said tubes while they are still mounted on the machine. Therehas indeed been proposed a friction welding machine which enables anouter upset appearing at the joint of welded tubes to be removed by acutting tool disposed on said machine. However, this friction weldingmachine has the drawback that said cutting tool is of a type which cutsoff the outer upset while the welded tubes are rotated, and consequentlythat if the tube which is made to rotate is fitted with an elbow, thecutting of the outer upset will be impossible. Moreover, theabove-mentioned type of the prior art friction welding machine isincapable of removing outer and inner upsets produced at the joint of atube and an elbow while they are still mounted on the machine.

, It is accordingly an object of this invention to provide a frictionwelding machine which enables elongate tubes to be unfailinglyfriction-welded and, in addition, outer and inner upsets appearing atthe joint of welded tubes to be easily cut off while they are stillplaced on the machine. I

Another object of the invention is to provide a friction welding machinecapable of friction-welding an elbow to a tube and removing outer andinner upsets occurring atthe joint of the elbow and tube.

According to an aspect of this invention, there isprovided a frictionwelding machine which comprises a bed; a stationaryhead for firmlyholding one tube fixed to one end of said bed in the lengthwisedirection of said bed; a movable head for chuckinganother tube near thatend at which it is friction-welded to said one tube so as to cause thefriction-welded ends of both tubes to face each other in exactconcentric relationship and rotating the chucked tube about its axis; awork rest for concentrically aligning both tubes in cooperation with themovable head; a tail stock for holding the opposite end of the chuckedtube to its frictionwelded end so as to press the chucked tube to saidone tube; a support provided at the other end of the bed so as to holdan inner upset-removing device inserted through both tubes; and an outerupset-removing device formed of a tool bit and fitted to the movablehead.

The movable head has a hollow spindle for allowing said another tube topenetrate therethrough and rotatable about its axis by a motor. Insideof that end portion of the hollow spindle which faces the fixed head andthe opposite end portion of said spindle are received chucks rotatableconcentrically with the hollow spindle, and closed with oil pressure soas to hold said another tube.

On that chucked surface of the movable head which faces the stationaryhead is mounted an outer upsetremoving device so as to rotate with saidmovable head. This outer upset-removing device may be replaced byanother type which consists of a single blade member whose inner edgeconstitutes a helical blade having a circular cross section or two blademembers whose inner edges respectively constitute a helical blade havinga semicircular cross section and, when combined, present a circularcross section. This modified type of outer upset-removing device may beprovided on that side of the stationary head which is disposed oppositeto the end face of the movable head or that side of the movable headwhich faces the stationary head.

An inner upset-removing device consists of a blade member whose outeredge constitutes a helical blade having a circular cross section or twoblade members whose outer edges respectively constitute a helical bladehaving a semicircular cross section and, when combined, present acircular cross section, and is fixed to a support rest by means of ashaft. Alternatively, to cut off an inner upset occurring at the jointof a tube and an elbow, it is advised to rotate an arm having a circularcross section and curved complementarily with the inner wall of theelbow about the center of said curvature and pivotally attach a blademember to one end of said arm.

This invention will be described by way of examples with reference tothe accompanying drawings, in which:

FIG. 1 is a plan view of a friction welding machine according to anembodiment of this invention;

FIG. 2 is a front view of FIG. 1;

FIG. 3 is a cross sectional view on line 3-3 of FIG. 1, showing thestructure of a stationary head; V

FIG. 4 is a cross sectional view on line 4-4 of FIG. 1, showing thestructure of a movable head;

FIG. 5 is a cross sectional view on line 5-5 of FIG. 1, indicating thestructure of a work rest;

FIG. 6 is a cross sectional view on line 66 of FIG. 1, presenting thestructure of a tail stock;

FIG. 7 is a cross sectional view on line 7-7 of FIG. 1, illustrating thestructure of the support of an inner upset-removing device;

FIG. 8 shows the clamping means of the tail stock;

FIG. 9 indicates the clamping means of the inner upset-removing device;

FIG. 10 is a fractional cross sectional view of a movable head;

FIG. 11 is a cross sectional view on line IlII of FIG.

FIG. 12 is a fractional cross sectional view of the chucked portion ofthe tail stock;

FIG. 13 presents the manner in which an inner upset is removed by aninner upset-removing device according to an embodiment of the inventionincluded in the friction welding machine thereof;

FIG. 14 illustrates a blade member according to a embodiment of theinvention;

FIG. 15 is a perspective view of the blade member of FIG. 14;

FIG. 16 indicates a blade member according to another embodiment of theinvention;

FIG. 17 is a developed view of the blade member of FIG. 14;

FIG. 18 is a developed view of the blade member of FIG. 16;

FIG. 19 is a fractional cross sectional view of the .present frictionwelding machine, where the blade upset grown at the joint of a tube andan elbow;

FIG. 20 is a front view of an outer upset-removing device according toan embodiment of the invention;

FIG. 21 is a cross sectional view on line 2121 of FIG. 20; and

FIG. 22 shows a cutter according to an embodiment of the invention usedin the outer upset-removing device of FIG. 20.

Referring to FIGS. 1 and 2, the friction welding machine of thisinvention comprises a bed 31; a stationary head 32 fixed to the leftupper surface of the bed 31; a movable head 33; a work rest 34; a tailstock 35; and a support 36 for an inner upset-removing device, all thesemembers except for the first mentioned being arranged on the bed 31 fromthe left to the right in the order mentioned.

As seen from FIGS. 1 and 3, there is fixed the cylinder of a hydraulicpiston cylinder assembly 38 to the rear side plate 37a (as viewed fromthe friction welding machine 30) of the housing 37 of the stationaryhead 32. A piston rod 39 extending from the piston of the pistoncylinder assembly 38 into the stationary head 32 causes a sliding memberwith an L-shaped cross section fixed to the end of the piston rod 39 toreciprocate along the bottom plate 37b of the stationary head 32. To theinner wall of the upright portion of the sliding member 40 is fixed asupport block 41. Opposite to this support block 41 is provided anothersupport block 42 which can make a reciprocating movement. The supportblock 42 is connected to the sliding member 40 through a link 44 havingits central part pivotally supported by an arm 43 extending from thefront side of a housing 37 into the interior thereof, another link 45pivotally supported at one end by the forward end of the sliding member40 and at the other end by the lower end of the link 44, and stillanother link 46 pivotally supported at one end by the support block 42and at the other end by the upper end of the link 44. The support block42 can move through the operation of the piston cylinder assembly 38 tothe same extent as the support block 41 in the opposite direction tothat in which the block 41 travels. Both support blocks 41 and 42 arefitted with a pair of mutually facing work holders 47, in which thereare cut out mutually facing engagement grooves 48 with a semicircularcross section extending parallel in the lengthwise direction of the bed31. When the work holders 47 are drawn near to each other by operatingthe piston cylinder assembly 38, then a tubular workpiece or tube 49 canbe firmly set in position parallel to the lengthwise direction of thebed 31.

Referring now to FIG. 4, the movable head 33 has its bottom providedwith a dovetail groove 51 engaging a dovetail formed on the uppersurface of the bed 31 so as to extend lengthwise thereof from thesubstantially central part of said bed 31 to the stationary head 32.Accordingly, the movable head 33 can slide along the dovetail 50lengthwise of the bed 31.

The movable head 33 contains a hollow spindle 52 (FIG. 10) rotatableabout the central axis A-A defined by the engagement grooves 48 of thework holders 47, said spindle 52 being driven by a motor 53 mounted onthe movable head 33. Inside of both end portions of the spindle 52,there are received chucks rotatable with the spindle 52 and designed, aslater described, to be closed with oil pressure and hold that end of atubular member or tube 54 which is to be frictionwelded to the aforesaidtube 49 already clamped by the work holders 47. On the bed 31 is formeda dovetail 55 extending from the substantially central part to the rightend of said bed 31.

Referring to FIGS. 5 to 7, the work rest 34, tail stock 35 and support36 of the inner upset-removing device respectively have dovetail grooves56, 57 and 58 cut out at the bottom for engagement with the dovetail 55.The work rest 34 and tail stock 35 are provided with hydraulicallyoperated chucks 59 and 60 respectively which rotate about the centralaxis A-A, while holding the central part and rear end portion of thetube 54 respectively. The chucks 59 are of the same structure asthosegof the later described movable head 33. The oil pressure chuck 60is, for example, a three-jaw type illustrated in FIG. 6. The jaws 61 ofthe chuck 60 of thetail stock 35 each have, as shown in FIG. 12, aninner wall 61a for holding the outer periphery of the rear end portion54a of the tube 54 and an abutment 62 disposed adjacent to said innerwall 61a and projecting into the chuck 60 so as to engage the rear endface 54b of the tube 54.

As seen from FIGS. 1 to 7, a pair of tension rods 63 and 64 parallel to,and symmetrical with respect to, the central axis A-A penetrate thestationary head 32, movable head 33, work rest 34, tail stock 35 and thesupport 36 of the inner upset-removing device. The tension rods 63 and64 each have the left end fixed to the pistons of hydraulic pistoncylinder assemblies 65 and 66 respectively, the cylinders of which areattached to the stationary head 32, thereby making reciprocatingmovements by the operation of said piston cylinder assemblies 65 and 66.v

The movable head 33 and tension rods 63 and 64 are fixed together forjoint movement by the operation of the piston cylinder assemblies 65 and66. On those parts of the tension rods 63 and 64 which are over theworking areas of the work rest 34 and tail stock 35 are formedengagement sections 67 and 68 consisting of saw teeth 67a and 68a, eachof which has a cross section tapering to the right.

The work rest 34 and tail stock 35 are provided with clamping mechanisms69 and 70 for locking said work rest 34 and tail stock 35 with thecorresponding engagement sections 67 and 68 of the tension rods 63 and64. As shown in FIG. 8, these clamping mechanisms 69 and 70 eachcomprise a cylinder 71 fixed to the work rest 34 and tail stock 35; ahydraulically operated piston 72 fitted into said cylinder 71; and anengagement strip 74 fixed to a piston rod 73 by a screw disposed at theend thereof and provided with teeth 74a matching those of the engagementsections 67 and 68 of the tension rods 63 and 64 when compressed oil isintroduced into the cylinder 71, the piston 72 is driven with theresultant engagement of the engagement strip 74 with the engagementsections 67 and 68 of the tension rods 63 and 64, thereby causing thework rest 34 and tail stock 35 to be clamped by the tension rods 63 and64. Conversely, where compressed oil is drawn off from the cylinder 71,the engagement strip 74 is released from the engagement sections 67 and68 to set the work rest 34 and tail stock 35 free from the tension rods63 and 64.

On those parts of the tension rods 63 and 64 which are over the workingarea of the support 36 of the inner upset-removing device is formed, asshown in FIG. 9,

an engagement section 75 consisting of saw teeth 75a,

each of which has a cross section tapering to the left. The support 36is fitted with a clamping mechanism 76 of a similar structure to thoseof the work rest 34 and tail stock 35 in order to be locked with theabovementioned engagement section 75. In the clamping mechanism 76 ofthe support 36, a cylinder 77 fixed to the support 36 corresponds to thecylinder 71 of the clamping mechanisms 69 and 70, a piston 78 to thepiston 72, a piston rod 79 to the piston rod 73 and an engagement strip80 to the engagement strip 74. It will be noted that since the teeth 80aof the engagement strip 80 each bear a shape matching those of theengagement section-75, the teeth 80a are tapered in the oppositedirection to the teeth 74a of the engagement strip 74.

To the right end of the support 36 is fixed the cylinder of a hydraulicpiston cylinder assembly 81. To the piston is fixed a narrow supportingrod 82 disposed in alignment with the central axis AA and extending nearthe stationary head 32 so as to reciprocate with the piston of saidassembly 81.

Referring to FIG. 13, a cutter head 83 for removing an inner upset isfixed by a nut 84 to the end 82a of the supporting rod 82. The cutterhead 83 consists, as shown in FIGS. 13 to 15, of a frustum-shaped cutter85 tapering toward the stationary head 32; a mount 86 integrally formedon that side of the cutter 85 which faces the stationary head 32; and apair of cutting edges 87 each provided on that outer periphery of thecutter 85 which faces the support 36 in a helical form extending alongthe semicircular section of said outer periphery, the maximum diameter Bof a circle defined by said paired cutting edges 87 being chosen to besubstantially equal to the inner diameter C of the tubes 49 and 54. Thecutter head 83 has a concentrically formed female screw 88, into whichthere is fitted a male screw formed at the end 82a of the supporting rod82, said male screw engaging a nut 84. FIG. 17 is a developed view ofthe cutting edges 87 of the cutter head 83 in FIGS. 13 to 15. The cutterhead 83 and operating rod 82 constitute an inner upset-removing device200. As shown in FIG. 16, the paired cutting edges 87 in FIGS. 13 to maybe replaced by a single cutting edge extending along the entireperiphery of the cutter head 83. FIG. 18 is a developed view of saidsingle cutting egdge 87.

Referring to FIG. 10, that wall 89 of the movable head 33 which facesthe stationary head 32 is fitted with a hydraulic piston cylinderassembly 90 disposed coaxially with the central axis AA. Theaforementioned hollow spindle 52 penetrates the movable head 33. Theleft end 52a of the spindle 52, namely, that end which faces thestationary head 32 has an increased inner diameter, wherein there isreceived a collet chuck 191 having the same slots as in a conventionalcollet chuck formed in the axial direction so as to have its diameterbroadened by its own elasticity. The right and left peripheral endportions of said collet chuck 191 constitute tapered planes 191a and191b whose diame ter gradually decreases toward the end face. That innerwall of the hollow spindle 52 which faces the tapered plane 19112constitutes a tapered plane 52b so as to match said tapered plane 191b.

The cylinder unit 91 of a piston cylinder assembly 90 consists of aflange 93 fixed to a wall 89 by bolts 92, a hollow shaft 94 extending tothe right from the flange 93 into the wall 89 and a cylinder 95extending to the left from the flange 93. The hollow spindle 52 isrotatably received in the hollow shaft 94 by means of a ra-' dialbearing 96.

The right inner wall portion 97 of the cylinder 95 has a smaller innerdiameter and the left inner wall portion 98 thereof has a larger innerdiameter. The left and right portions 100 and 101 of a piston 99 have asmaller diameter and the central portion 102 thereby has a largerdiameter. The smaller diameter portion 101 and larger diameter portion102 of the piston 99 slidably contact the smaller inner diameter portion97 and larger inner diameter portion 98 of the cylinder 95 respectively.To the left end of the cylinder 95 is fixed a ring-shaped end plate 103by screws 104 to close said left end. Against the inner periphery of ablind hole 105 formed in the inner wall of the end plate 103 slidablyabuts the smaller diameter portion 100 of the piston 99. The smallerdiameter portions 100 and 101 and larger diameter portion 102 of thepiston 99 have such lengths that the piston 99 can reciprocate :in theaxial direction with these three portions 100, 10land 102 in slidablecontact with the inner periphery of the blind hole 105 of the end plate103, the smaller inner diameter portion 97 of the cylinder 95 and thelarger inner diameter portion 98 of said cylinder 95 respectively.

Between the piston 99 and the left end portion 52a of the hollow spindle52 is positioned a slider 106. On the inner wall of the slider 106 isformed a spline 107 extending in the axial direction, said spline 107engaging another spline 108 provided on the outer periphery of the leftend portion 52a of the hollow spindle 52 so as to slide in the axialdirection (see FIGS. 10 and 11). The slider 106 is provided with aflange 109 on the left side outer periphery and also with a ring-shapedabutment 110 on the right side outer periphery, said abutment 110 beinglocated by a ring nut 111. These flange 109 and abutment ll0clamp aflange 113 extending inward from the central part of the piston 99 bymeans of thrust bearings 112.

Into the end plate 103 is rotatably fitted a pusher 114 for operatingthe collet chuck 191 through a sleeve 1 15. Said pusher 114 is fixed tothe left end face of the slider 106. The inner wall of the :right sideportion of the pusher 114 constitutes a tapered plane 114a to match theleft side tapered plane 191a of the collet chuck 191.

The cylinder 95 is bored with compressed oil ports 119 and 120respectively communicating with a chamher 117 defined by said cylinder95, the end plate 103, and the larger diameter portion 102 and smallerdiameter portion 101 of the piston 99 and also with a chamber 118defined by said cylinder 95 and the larger diameter portion 102 andsmaller diameter portion 101 of said piston 99.

To the left end face of the pusher 114 is fitted an outer upset-removingdevice 121 which consists of a cutting tool 122 whose cutting edge 122aextends inward in the radial direction so as to substantially abutagainst the tube 54 and a fixture 123 for fixing said cutting tool 122to the left end face of the pusher 114. For simplification, FIG. 1 lomits said outer upset-removing device 121. Also on the opposite side ofthe movable head 33 to the stationary head 32 is provided a chuckingpiston cylinder assembly 90 having the same structure as shown in FIG.10.

There will now be described the operation of a friction welding machineaccording to this invention.

A tube 54 is inserted into the friction welding machine from the leftside of the stationary head 32 and further pushed through the hollowspindle 52 of the movable head 33 and the chucks 59 of the work rest 34so as to cause the right end 54a of the tube 54 abut against theabutment 62 of the chuck 60 of the tail stock 35. When the tube 54 isintroduced into the friction welding machine, the supporting rod 82having its end fitted with the cutter head 83 gradually approaches theleft side of the tube 54. When the right end of the tube 54 strikes theabutment 62, the left end of said tube 54 is brought, as shown in FIGS.1, 2 and 10, to the prescribed position between the stationary head 32and movable head 33.

Another tube 49 is inserted between the work holders 47 from the leftside of the stationary head 32, such that the right end of the tube 49contacts the left end of the first mentioned tube 54. Thereafter, thecutter head 83 disposed at the end of the operating rod 82 is made topass through the left end of the tube 54 into the tube 49 by moving thesupport 36 of the inner upset-removing device 200 toward the stationaryhead 32.

When the above-mentioned preparatory steps have been taken, the pistoncylinder assemblies 38 of the stationary head 32 are operated to closethe work holders 47, thereby fixing the tube 49 to the stationary head32. When, in FIG. 10, compressed oil is conducted into the chamber 117through the port 119 bored in the cylinder 95 of the movable head 33,then the piston 99 travels to the right, causing the slider 106 andpusher 114 also to move to the right through the thrust bearings 112.Since the tapered plane 114a of the pusher 114 is pressed against thetapered plane 191a of the collet chuck 191, saidchuck 191 is closed toclamp the tube 54. (When compressed oil enters the chamber 118 throughthe port 120, the piston 99 moves to the left to reverse theabove-mentioned operation, with the result that the collet chuck 191 isopened and the tube 54 is released.) The clamping mechanisms 69, 70 and76 of the work rest 34, tail stock 35 and support 36 respectively can beoperated to let the engagement strips 74 and 80 engage the engagementsections 67, 68 and 75 of the tension rods 63 and 64 (see FIGS. 8 and9). The chucks 59 and 60 of the work rest 34 and tail stock 35respectively are closed to clamp the tube 54.

With the clamping mechanisms 69 and operated as above-mentioned, themotor 53 (FIGS. 1 and 2) of the movable head 33 is driven quickly torotate the tube 54 through the hollow spindle 52, splines 107 and 108and collet chucks 191. When, under this condition, the piston cylinderassemblies 65 and 66 of the stationary head 32 are operated to cause thetension rods 63 and 64 to move to the left, then the tube 54 also movesto the left to the same extent as the tension rods 63 and 64 togetherwith the movable head 33, work rest 34 and tail stock 35. Accordingly,the tube 54 rotates with the left end pressed against the right end ofthe tube 49. The abutting parts of both tubes 54 and 49 are considerablyheated by friction and are brought to a state easily weldable underpressure. In this case, the clamping mechanism 76 remains open toprevent the support 36 from moving to the left. When this condition isattained, the motor 53 is brought to rest so as to stop the rotation ofthe tube 54. Further, the piston cylinder assemblies 65 and 66 areoperated to move the tension rods 63 and 64 to the left, causing theleft end of the tube 54 to be forcefully pressed against the right endof the tube.49. When allowed to cool for a certain length of timedefined by the type of both tubes 49 and 54, they are fullyfriction-welded.

When both tubes 49 and 54 are thus friction-welded, there are grown, asshown in FIGS. 10 and 13, an inner upset 124 inside of the joint of thewelded tubes 49 and 54 and an outer upset 125 outside of said joint.

After completion of friction welding, the work rest 34 and tail stock 35are released from the clamping mechanisms 69 and 70. Compressed oil isconducted into the chamber 118 through the port to open the collet chuck191 (FIG. 10). The motor 53 is driven to rotate the cutting tool 122through the slider 113 and pusher 114. The piston cylinder assemblies 65and 66 are operated again to move the tension rods 63 and 64 to theleft. Then the movable head 33 alone travels to the left together withthe tension rods 63 and 64, while the tube 54 is brought to rest.Accordingly, the outer upset is removed by the cutting edge 122a of thecutting tool 122. When the clamping mechanism 76 of the support 36 isoperated to clamp the support 36 to the tension rods 63 and 64, and thesupporting rod 82 is made to move to the right side of FIGS. 1 and 2 byoperating the piston cylinder assembly 81, then the cutter head 83travels with the supporting rod 82 in the direction of the arrow Dindicated in FIG. 13 so as to cut off the inner upset 124 by the cuttingedge or edges 87 (FIGS. 15 or 16).

Referring to FIG. 8, where the engagement strips 74 of the clampingmechanisms 69 and 70 of the work rest 34 and tail stock 35 engage theengagement sections 67 and 68 of the tension rods 63 and 64, then thetension rods 63 and 64 unfailingly cause the tube 54 to move to the leftthrough the work rest 34 and tail stock 35.

Referring to FIG. 9, where the engagement strip 80 of the clampingmechanism 76 of the support 36 engages the engagement sections 75 of thetension rods 63 and 64 and the piston cylinder assembly 81'moves thecutter head 83 (FIG. 13) to the right through the supporting rod 82,then the support 36 is prevented from traveling to the left by aleftward acting reactional force F applied to said support 36.

Where the tension rods 63 and 64 are moved to the left with theengagement strip 74 of the clamping mechanism 70 of the tail stock 35engaged with the engagement sections 67 and 68 of the tension rods 63and 64, then the abutment 62 formed, as shown in FIG. 12, on the jaw 61of the chuck 60 of the tail stock 35 is pressed against the right end ofthe tube 54, causing said tube 54 to travel to the left to the sameextent as the leftward movement of the tension rods 63 and 64.

FIG. 19 represents the case where an elbow 126 is friction-welded to thetube 49 mounted on the immovable head 32. The elbow 126 is supported bya holding member 127 having a shaft 128 clamped by the collet chucks 191of the movable head 33. The cutter head 83 (of the same structure asshown in FIGS. 13 to for removing the inner upset 124 has a shaft 129projecting to the left. The right end 129a of said shaft 129 is pivotedby a pivot 131 to the left end 130a of a mandrel 130 movable in theelbow 126 along its curved axis. That part of the holding member 127which faces the center of the curvature of the elbow 126 is fitted witha pivot 132. TO this pivot 132 is pivoted one end 133b of an arm 133having the other end 133a connected to the right end 130b of the mandrel130.

Where, in the embodiment of FIG. 19, the arm 133 rotates about the pivot132 in the direction of the arrow E, then the cutter head 83 movesrightward to cut off the inner upset 124. It is also possible to causethe shaft 128 of the holding member 127 to be clamped between the workholders 47 of the stationary head 32 instead of letting said shaft 128be held by the collet chucks 191 of the movable head 133. Under thiscondition, the elbow 126 is friction-welded to the tube 54.

FIGS. to 22 illustrate an outer upset-removing device according toanother embodiment of this invention. This outer upset-removing device134 may be fixed to the pusher 114 of the piston cylinder assembly 90disposed on that side of the movable head 33 which faces the stationaryhead 32 or to the right end plate 37b of the stationary head 32.

The outer upset-removing device 134 consists of a pair of cutting tools135 and 136 each having a semicircular cross section and a pair offitting parts 137 and 138. The cutting tools 135 and 136 each consist,as shown in FIG. 22, of a flange 139 and a cutting element 141 whoseinner edge constitutes a slightly helical blade 140 having asemicircular cross section. The fitting parts 137 and 138 are in asemicircular form and consist of cutting tool-fitting sections 1370 and138a to which the flanges 139 of the cutting tools 135 and 136 arefitted by bolts 142 and fixing members 137b and 138b which extend to theright and left of said cutting tool-fitting sections 137a and 138arespectively and are fixed to the right end plate 37b of the stationaryhead 32.

Where, in the embodiment of FIGS. 20 to 22, the tube 49 is released fromthe work holders 47 by operating the piston cylinder 38 (FIG. 1) afterfriction welding of said tube 49, and the tubes 49 and 54 are jointlymoved in the direction of the arrow G indicated in FIG. 21, then theouter upset 125 is cut off by the cutting edges 140 of the cutting tools135 and 136.

The cutter head 83 of the inner upset-removing device 200 shown in FIGS.13 to 15 and the cutting tools 135 and 136 of the outer upset-removingdevice shown 6 A-A. When the inner and outer upsets are removed,

cutting forces are applied in symmetrical relationship to the joint ofthe tubes 49 and 54,. so that said removal can be effected smoothly. Theinner and outer upsetremoving devices may have one or more than two cutting edges.

What we claim is:

l. A friction welding machine comprising:

a bed;

a stationary head fixed to the upper surface of one end portion of thebed and provided with work holders for clamping a first tube in thelengthwise direction of the bed;

a movable head disposed on the bed adjacent to the stationary head so asto slide lengthwise of the bed and provided with a first chucking meansfor clamping one end portion of a second tube brought closely to facethe first tube in concentric relationship therewith;

a motor received in the movable head to rotate the first chucking means;

a work rest provided on the bed adjacent to the opposite side of themovable head to the stationary head so as to slide lengthwise of the bedand fitted with a second chucking means for clamping the central part ofthe s'econd tube so as to enable it to rotate concentrically with thefirst tube;

a tail stock positioned adjacent to the opposite side of the work restto the movable head so as to slide lengthwise of the bed and equippedwith a third chucking means for clamping the other end of the secondtube by being engaged] with said other end;

a support mounted on the bed adjacent to the opposite side of the tailstock to the work rest so as to slide lengthwise of the bed;

an inner upset-removing device comprising a sup porting rod extendingfrom the support toward the stationary head concentrically with the Isecond tube and a cutter head fitted to that end of the supporting rodwhich faces the stationary head;

an outer upset-removing device for cutting off an outer upset grown atthe joint of the first and second tubes;

a pair of tension rods penetrating the movable head,

work rest, tail stock and support in parallel relationship with the bedand symmetrically with respect to the central axis so as to reciprocatelengthwise of the bed, said movable head being fixed to the tension rodsfor joint reciprocation therewith;

a first clamping mechanism for effecting engagement.

and disengagement between the work rest and tension rods; a secondclamping mechanism for effecting engagement and disengagement betweenthe tail stock and tension rods; and

a third clamping mechanism for carrying out engagement and disengagementbetween the support and tension rods, wherein the mutually facing endsof the first and second tubes are pressed against each other, both tubesare subjected to relative rotation to heat the mutually facing ends to asufficiently high temperature to attain friction welding, the mutuallyfacing ends are more forcefully pressed against each other to effect thefriction welding of both tubes, and thereafter inner and outer upsetsoccurring at the joint of the first and second tubes are cut off whilewelded tubes are still mounted on the friction welding machine.

2. A friction welding machine according to claim 1 characterized in thatthe movable head contains a hollow spindle rotated by the motorconcentrically with the first and second tubes, and that the firstchucking means comprises a first cylinder fixed to the movable headconcentrically with the first and second tubes, a first piston receivedin the first cylinder so as to reciprocate by compressed oil in theaxial direction of the first cylinder, a slider received in the firstpiston and made to reciprocate with the first piston in the axialdirection of the first cylinder, a pusher fixed to one end of theslider, and a collet chuck concentrically disposed in the hollow spindleso as to be operated by the reciprocation of the pusher.

3. A friction welding machine according to claim 2 wherein said outerupset-removing device comprises a cutting tool having a cutting edgethereof engageable with the tubes and a fixture for fixing the cuttingtool to the pusher of the first chucking means, whereby an outer upsetgrown at the joint of the first and second tubes is cut off by the outerupset-removing device.

4. A friction welding machine according to claim 1 whereinthe outerupset-removing device is fixed to the stationary head concentricallywith the first tube, said outer upset-removing device comprising morethan one cutting tool having the inner peripheral surface provided withhelical cutting edges having a semicircular cross section for cuttingoff an outer upset appearing at the joint of the first and second tubes.

5. A friction welding machine according to claim 1 wherein the outerupset-removing device is fixed to the movable head concentrically withthe first tube, said outer upset-removing device comprising more thanone cutting tool having the inner peripheral surface provided with morethan one helical cutting edges for cutting off an outer upset grown atthe joint of the first and second tubes.

6. A friction welding machine according to claim 1 wherein the cutterhead has the outer peripheral surface thereof provided with helicalcutting edges having a semicircular cross section.

7. A friction welding machine according to claim I wherein the tensionrods are each provided with first engagement sections bearing saw teetheach having a cross section tapering toward the stationary head over theworking area of the work rest and the tail stock and a second engagementsection bearing saw teeth each having a cross section reversely taperingtoward the stationary head over the working area of the support; thefirst and second clamping mechanisms are provided with engagement stripsengageable with the saw teeth of the first engagement sections of thetension rods by the operation of said clamping mechanisms so as to clampthe work rest and tail stock to the tension rods; and the third clampingmechanism is provided with an engagement strip engageable with the sawteeth of the second engagement sections of the tension rods by theoperation of said clamping mechanism so as to clamp the support to thetension rods.

8. A friction welding machine according to claim 1 wherein the thirdchucking means is provided with jaws each comprising an inner surfacefor holding the rear outer peripheral surface of the second tube and anabutment disposed adjacent to said inner surface and projecting into thethird chucking means so as to engage the rear end face of the secondtube.

1. A friction welding machine comprising: a bed; a stationary head fixedto the upper surface of one end portion of the bed and provided withwork holders for clamping a first tube in the lengthwise direction ofthe bed; a movable head disposed on the bed adjacent to the stationaryhead so as to slide lengthwise of the bed and provided with a firstchucking means for clamping one end portion of a second tube broughtclosely to face the first tube in concentric relationship therewith; amotor received in the movable head to rotate the first chucking means; awork rest provided on the bed adjacent to the opposite side of themovable head to the stationary head so as to slide lengthwise of the bedand fitted with a second chucking means for clamping the central part ofthe second tube so as to enable it to rotate concentrically with thefirst tube; a tail stock positioned adjacent to the opposite side of thework rest to the movable head so as to slide lengthwise of the bed andequipped with a third chucking means for clamping the other end of thesecond tube by being engaged with said other end; a support mounted onthe bed adjacent to the opposite side of the tail stock to the work restso as to slide lengthwise of the bed; an inner upset-removing devicecomprising a supporting rod extending from the support toward thestationary head concentrically with the second tube and a cutter headfitted to that end of the supporting rod which faces the stationaryhead; an outer upset-removing device for cutting off an outer upsetgrown at the joint of the first and second tubes; a pair of tension rodspenetrating the movable head, work rest, tail stock and support inparallel relationship with the bed and symmetrically with respect to thecentral axis so as to reciprocate lengthwise of the bed, said movablehead being fixed to the tension rods for joint reciprocation therewith;a first clamping mechanism for effecting engagement and disengagementbetween the work rest and tension rods; a second clamping mechanism foreffecting engagement and disengagement between the tail stock andtension rods; and a third clamping mechanism for carrying out engagementand disengagement between the support and tension rods, wherein themutually facing ends of the first and second tubes are pressed againsteach other, both tubes are subjected to relative rotation to heat themutually facing ends to a sufficiently high temperature to attainfriction welding, the mutually facing ends are more forcefully pressedagainst each other to effect the friction welding of both tubes, andthereafter inner and outer upsets occurring at the joint of the firstand second tubes are cut off while welded tubes are still mounted on thefriction welding machine.
 2. A friction welding machine according toclaim 1 characterized in that the movable head contains a hollow spindlerotated by the motor concentrically with the first and second tubes, andthat the first chucking means comprises a first cylinder fixed to themovable head concentrically with the first and second tubes, a firstpiston received in the first cylinder so as to reciprocate by compressedoil in the axial direction of the first cylinder, a slider received inthe first piston and made to reciprocate with the first piston in theaxial direction of the first cylinder, a pusher fixed to one end of theslider, and a collet chuck concentrically disposed in the hollow spindleso as to be oPerated by the reciprocation of the pusher.
 3. A frictionwelding machine according to claim 2 wherein said outer upset-removingdevice comprises a cutting tool having a cutting edge thereof engageablewith the tubes and a fixture for fixing the cutting tool to the pusherof the first chucking means, whereby an outer upset grown at the jointof the first and second tubes is cut off by the outer upset-removingdevice.
 4. A friction welding machine according to claim 1 wherein theouter upset-removing device is fixed to the stationary headconcentrically with the first tube, said outer upset-removing devicecomprising more than one cutting tool having the inner peripheralsurface provided with helical cutting edges having a semicircular crosssection for cutting off an outer upset appearing at the joint of thefirst and second tubes.
 5. A friction welding machine according to claim1 wherein the outer upset-removing device is fixed to the movable headconcentrically with the first tube, said outer upset-removing devicecomprising more than one cutting tool having the inner peripheralsurface provided with more than one helical cutting edges for cuttingoff an outer upset grown at the joint of the first and second tubes. 6.A friction welding machine according to claim 1 wherein the cutter headhas the outer peripheral surface thereof provided with helical cuttingedges having a semicircular cross section.
 7. A friction welding machineaccording to claim 1 wherein the tension rods are each provided withfirst engagement sections bearing saw teeth each having a cross sectiontapering toward the stationary head over the working area of the workrest and the tail stock and a second engagement section bearing sawteeth each having a cross section reversely tapering toward thestationary head over the working area of the support; the first andsecond clamping mechanisms are provided with engagement stripsengageable with the saw teeth of the first engagement sections of thetension rods by the operation of said clamping mechanisms so as to clampthe work rest and tail stock to the tension rods; and the third clampingmechanism is provided with an engagement strip engageable with the sawteeth of the second engagement sections of the tension rods by theoperation of said clamping mechanism so as to clamp the support to thetension rods.
 8. A friction welding machine according to claim 1 whereinthe third chucking means is provided with jaws each comprising an innersurface for holding the rear outer peripheral surface of the second tubeand an abutment disposed adjacent to said inner surface and projectinginto the third chucking means so as to engage the rear end face of thesecond tube.